The Internet and World Wide Web provide users with various types of web content such as web pages and other web documents. For instance, the Internet may enable users to access a multitude of information including, among other things, local news reports (e.g., local, national, and world news), weather reports, sports scores, encyclopedia entries, online dictionaries, and other sources of information. Due to the large amount of information available, various tools, such as search engines, have been developed to help users find web content pertaining to a particular topic. Search engines may enable users to search web content by keyword. For example, in response to receiving a keyword from a user, a search engine may return a list of web pages that include the keyword. In other words, search engines may enable a user to quickly locate and retrieve particular web content associated with specific search topics of interest.
In some cases, web content, such as web pages and other web documents, may collectively provide insight into web activity associated with particular topics. For example, a large number of web pages with references to a particular search topic (e.g., a new book or movie) may indicate a high level of web activity for the search topic. Similarly, a small number of web pages with references to a particular search topic may indicate a low level of web activity for the search topic. However, search engines and other tools for finding information on the Internet and World Wide Web typically do not provide users with indications of trends of web content levels for particular search topics.